Engine oil additive composition comprising nanodiamond and method for preparing same

ABSTRACT

The present invention relates to an engine oil additive composition, whereby a hydrophobically surface-modified nanodiamond is capable of being stably dispersed in oil for a long time by being used together with a specific dispersant. According to the present invention, the nanodiamond is stably dispersed in the engine oil for a long time, thereby reducing friction and abrasion of the machine such as an engine and thus improving fuel efficiency.

TECHNICAL FIELD

The present invention relates to an engine oil additive composition, and a method for preparing the same, and in particular to an engine oil additive composition wherein nano-diamond is enough dispersed in oil.

BACKGROUND ART

An engine oil in general has a function which allows to reduce any friction between metals, cool heat of an engine component in such a way to discharge to the outside a high temperature heat which occurs in the inside, easily obtain a pumping operation to key engine components at a low temperature, keep clean inner components in such a way to remove harmful residues and keep a stability at a high temperature, whereby it is possible to enhance fuel efficiency. More specifically, such an engine oil may perform a lubrication operation, a cooling operation, an anticorrosion operation, a cleaning operation, etc. in a vehicle, a ship, an airplane, etc. which equips with an internal combustion engine, thus performing an important operation which is related to a performance exhibition with respect to a low fuel efficiency in an internal combustion engine.

The above performance may be degraded due to the accumulation of contamination in oil and a chemical change which may easily occur in oil, in particular, due to a generation of an oxide product.

The key reason why such contaminants accumulate in the engine is that abrasion occurs due to the friction between metals since oil is not appropriately fed during the operation of the engine. In particular, such abrasion may occur a lot when the engine starts. This matter occurs since oil is not appropriately fed when the engine starts because oil is formed of a fluidic substance. In case where the engine is in a high temperature state, abrasion may frequently occur since an oil film is not smoothly formed.

The metal wherein abrasion has occurred, may be oxidized since it can easily react with other chemical additives in oil or may produce a secondary oxide product, which may have bad effect on the engine.

To this end, as a way to enhance the performance of the engine oil, some research and developments on an engine oil additive or an engine oil composition containing the same have been widely conducted. In recent years, a technology to enhance a wear resistance in such a way to add nano-diamond to an engine oil is being developed.

The Korean patent registration number 10-1205640 discloses a method for preparing a nano-diamond the surface of which is processed into a hydrophobic state using a fatty acid and a lubricant containing the same, which discloses a configuration for preparing nano-diamond the surface of which is processed into a hydrophobic state and which configuration includes a step for preparing a first mixture by adding nano-diamond to oil; a step for preparing a second mixture by adding to the first mixture a mono unsaturated fatty acid and an amine compound; and a step for processing the second mixture with an ultrasonic wave or milling it with a ball mill and a feature wherein an abrasion characteristic is good since the lubricant containing the thusly prepared nano-diamond has a low friction factor.

In case of the Korean patent registration number 10-1205640, there may be a problem providing a stable dispersion for a long time which may be performed only with a dispersion stability of nano-diamond particles the surfaces of which are processed into a hydrophobic state.

To this end, the inventors of the present application have made the present invention as a result of a research on an engine oil additive composition wherein it is possible to stably disperse hydrophobic nano-diamond particles in oil for a long time.

DISCLOSURE OF INVENTION

Accordingly, it is an object of the present invention to provide an engine oil additive composition which may allow a nano-diamond to be stably dispersed in engine oil for a long time.

It is another object of the present invention to provide an engine oil additive composition which may improve fuel efficiency in such a way that nano-diamond the surface of which is modified into a hydrophobic state improves a lubricating function of engine oil.

To achieve the above objects, there is provided an engine oil additive composition, which may include, but is not limited to,

a base oil;

a nano-diamond the surface of which is modified into a hydrophobic state; and

a dispersion agent which is formed of oleylamine, polyalkenyl succinimide, and oleic acid.

The engine oil additive composition may include, but is not limited to,

60˜99% by weight of a base oil;

0.001˜0.5% by weight of nano-diamond the surface of which is modified into a hydrophobic state;

a dispersion agent which is formed of 0.05˜10% by weight of oleylamine, 0.01˜5% by weight of polyalkenyl succinimide, and 0.5˜35% by weight of oleic acid.

According to another aspect of the present invention, the nano-diamond the surface of which is modified into a hydrophobic state may be prepared by:

a process (first step) wherein the nano-diamonds are treated with one or more of acids selected from a group consisting of hydrochloric acid, nitric acid, sulfuric acid and hydrogen peroxide;

a process (second step) wherein the nano-diamonds acid-treated in the first step are reacted with one or more of acid chlorides selected from a group consisting of thionyl chloride, phosphorous trichloride, and phosphorous pentachloride; and

a process (third step) wherein the nano-diamonds obtained in the second step are reacted with alkyl amine having 16˜18 carbons.

It is preferred that the polyalkenyl succinimide is polyisobutenyl succinimide, and the polyisobutenyl group has an average molecular weight of 300˜10,000.

In addition, according to another aspect of the present invention, there is provided a method for preparing an engine oil additive composition which may include, but is not limited to:

treating (first step) nano-diamonds with one or more of acids selected from a group consisting of hydrochloric acid, nitric acid, sulfuric acid and hydrogen peroxide;

reacting (second step) the nano-diamonds acid-treated in the first step with one or more of acid chlorides selected from a group consisting of thionyl chloride, phosphorous trichloride, and phosphorous pentachloride;

reacting (third step) the nano-diamonds obtained in the second step with alkyl amine having 16˜18 carbons, thus preparing nano-diamonds the surfaces of which are modified into a hydrophobic state;

obtaining (fourth step) a dispersed thing by mixing the nano-diamonds the surfaces of which are modified into a hydrophobic state, with oleylamine and dispersing with ultrasonic waves; and

inputting (fifth step) polyalkenyl succinimide, oleic acid, and a base oil into the dispersed thing obtained in the fourth step and dispersing with ultrasonic waves.

The configuration of the present invention will be described in detail.

The engine oil additive composition according to the present invention may include, but is not limited to, a) a base oil; b) a nano-diamond the surface of which is modified into a hydrophobic state; and c) a specific dispersion agent which is formed of oleylamine, polyalkenyl succinimide, and oleic acid.

The a) base oil used in the present invention may be selected from a group consisting of a mineral oil and a synthetic oil which is used as a base oil of a lubricating oil for a typical internal combustion engine, which is not limited thereto.

The mineral oil is an oil with a high boiling point which may be obtained by a vacuum distillation method from crude oil and is a colorless transparent oil which may be obtained through an isomerization in such a way to remove an unsaturated double bond or a ring compound through a purification process, for example, a hydrogenization treatment, etc.

Meanwhile, the synthetic oil, which is a synthesized oil, may be PAO (poly-α-olefin, poly-α-olefin), polyolester, wax cracking hydrocarbon, etc.

In the present invention, the base oil may be prepared and used in such a way to combine one kind or two or more of the mineral oil and the synthetic oil.

The base oil may be used in a range of 60˜99% by weight with respect to 100% by weight of the engine oil additive composition.

In the present invention, the nano-diamond particle which is a raw material b) may be used after its surface is modified into a hydrophobic state.

The nano-diamond particle used in the present invention is prepared by an explosion method. The average particle diameter thereof is 4˜6 nm, and an amorphous carbon compound may reside on its surface or the surface may be surrounded by an oxygen or hydrogen mixture, and most of particle grains are clotted into an aggregation.

In the method for modifying the surface of the nano-diamond particle into a hydrophobic state according to the present invention, a carboxyl group (ND—COOH) is formed on the surface of each of nano-diamond particles in such a way to treat the nano-diamond with an acid. Here, the acid used may be preferably obtained by combining one kind or two or more selected from a group consisting of hydrochloric acid, nitric acid, sulfuric acid and hydrogen peroxide.

When it needs to coat a carboxyl group on the surface of each of nano-diamond particles, it is preferred to combine hydrochloric acid, nitric acid, and hydrogen peroxide since a lot of oxygen contained in the hydrogen peroxide may facilitate the formation of carboxyl group. At this time, it is preferred that the combining ratio of acid is that hydrochloric acid: nitric acid: hydrogen peroxide is 2˜4:1:1 in a form of part by weight, and 3:1:1 is most preferred.

Next, the nano-diamond treated with acid in the first step is reacted with an acid chloride, and the carboxyl group formed on the surface of each of nano-diamond particles is substituted with a chloride acyl group (ND—COCl). At this time, as an acid chloride used, at least one kind may be used, which is selected from a group consisting of thionyl chloride (SOCl₂) which is an acid chloride of an inorganic acid, phosphorous trichloride (PCI3),and phosphorous pentachloride(PCI5), and the thionyl chloride is preferably used.

An alkyl amide group is formed by reacting alkyl amine with the nano-diamond particle wherein chloride acyl group has been formed. As the alkyl amine, it is preferred to use hexadecylamine which is alkyl amine with 16˜18 carbons, heptadecylamine and octadecylamine. In particular, when the octadecylamine is formed using octadecylamine with 18 carbons, it becomes possible to effectively have a long term stability in terms of dispersion when using with the dispersion agent of the present invention.

As mentioned above, the nano-diamond particles the surfaces of which are modified into a hydrophobic state since the octadecylamine is formed on the surface of the nano-diamond show a better dispersion as compared with when the nano-diamond particles before their surfaces are modified into a hydrophobic state are clotted in a base oil and are not dispersed.

In the present invention, it is preferred that the nano-diamond particles the surfaces of which are modified into a hydrophobic state are 0.001˜0.5% by weight with respect to 100% by weight of the whole engine oil additive composition, and it is more preferred to use 0.005˜0.1% by weight.

If the quantity of the nano-diamond particle is less than 0.001% by weight, it is hard to obtain any enhancement effect in terms of wear resistance with the aid of nano-diamond particles, and if the quantity thereof exceeds 0.5% by weight, it is not preferable since the quantity of the dispersion agent increases too much so as to maintain a stability in terms of dispersion of the nano-diamond particles.

Meanwhile, if only the nano-diamond particles which had octadecylamine on their surfaces were dispersed in the engine oil, it was confirmed that a long time stability in terms of dispersion was not good. To this end, the inventors of the present application have invented an engine oil additive composition of the present invention wherein a stable dispersion can be obtained even after a long time in such a way to combine specific dispersion agents.

More specifically, if the compounds of oleylamine, oleic acid and polyalkenyl succinimide are combined and used as a specific dispersion agent, the nano-diamond (ND-ODA) particles having octadecylamine on their surfaces can be dispersed stable for a long time.

In the present invention, as a succinimide compound, for example, a poly alkenyl succinimide, polyisobutenyl succinimide, morpholinopropyl polyisobutenyl succinimide, etc. may be used or morpholinopropyl octenyl succinimide, morpholinopropyl dodecenyl succinimide, dialkenyl succinimide, etc. may be used.

In the present invention, it is preferable to use the poly alkenyl succinimide, and it is more preferable to use the polyisobutenyl succinimide having a polyisobutenyl group the average molecular of which are 300 to 10,000.

As mentioned above, the engine oil additive composition of the present invention mixes the oleylamine with the nano-diamond particles the surfaces of which are modified into a hydrophobic state, namely, the ND-ODA particles, and the dispersion is performed for 10 minutes to 1 hour with ultrasonic waves, thus obtaining a dispersed thing. Into the dispersed thing, the polyalkenyl succinimide, the oleic acid and the base oil are inputted, and the dispersion is performed for 2 hours to 4 hours with ultrasonic waves, thus preparing the composition.

It is preferable to use 0.05˜10% by weight of oleylamine, 0.01˜5% by weight of polyalkenyl succinimide, and 0.5˜35% by weight of oleic acid with respect to 0.001˜0.5% by weight of the nano-diamond the surfaces of which are modified into a hydrophobic state with respect to 100% by weight of the whole engine oil additive composition, whereby it is possible to maintain a stability in terms of dispersion of nano-diamond particles for a long time.

Next, it is preferred that an engine oil additive composition of the present invention is 3-10 part by weight with respect to 100 part by weight of an engine oil.

Advantageous Effects

The engine oil additive composition according to the present invention may have effect on a stability in terms of dispersion of nano-diamond particles in an engine oil for a long time.

In addition, the engine oil additive composition of the present invention may have effect on an improvement in terms of fuel efficiency in such a way to reduce friction and abrasion since the nano-diamond can be dispersed stable for a long time in an engine oil.

The engine oil additive composition according to the present invention may have effect on an enhancement of service life of an engine oil in such a way to prevent any denaturalization of an engine oil, oxidation, etc. by reducing friction heat.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view illustrating a result of a FT-IR (Fourier Transform Infrared Spectroscopy) of a nano-diamond before an acid treatment.

FIG. 2 is a photo showing a particle cross section after a nano-diamond is analyzed with an AFT (Atomic Force Microscopy) before an acid treatment.

FIG. 3 is a view illustrating a FT-IR analysis data wherein it is possible to confirm that a COOH group is coupled to the surface of each of nano-diamond particles after an acid treatment.

FIG. 4 is a view illustrating a FT-IR analysis data wherein it is possible to confirm that an octadecylamine group is coupled to the surface of each of nano-diamond particles after the surface is modified into a hydrophobic state.

FIG. 5 is a view illustrating a result of a visual observation after the samples of embodiments 2˜3 and comparison examples 1˜8 are manufactured.

MODES FOR CARRYING OUT THE INVENTION

preferred embodiments of the present invention will be described. Such disclosures are not limited thereto and may be embodied in different ways. The descriptions below may be provided in an effort to enough transfer the concepts of the present invention to a person having ordinary skill in the art so that the disclosures herein can be implemented perfect and complete.

First Embodiment Preparation of Nano-Diamond Particles the Surfaces of Which are Modified into a Hydrophobic State

(1) Treatment with Acid

5 g of a nano-diamond (ND) powder was added to 120 mg of an acid solution wherein hydrochloric acid: nitric acid: hydrogen peroxide are mixed at ratio of 3:1:1, and the mixture was treated with ultrasonic waves for 4 hours. This solution was poured into distilled water and was rinsed until the filtering liquid becomes neutral. After filtration, a product was dried complete at 100° C., thus removing moisture. Thereafter, it was possible to obtain a particle (ND—COOH) wherein a COOH group is coupled onto the surface of the nano-diamond.

In case of the ND powder before an acid treatment, as a result of a FT-IR (Fourier Transform Infrared Spectroscopy) analysis, as illustrated in FIG. 1, a peak with respect to O—H and C—H was mainly obtained. As a result of an AFM (Atomic force Microscopy) analysis, a ND powder was clotted a lot due to effects of moisture in the air and a cohesive force of the powder itself. As it could be confirmed in the photo showing a cross section of each particle in FIG. 2, the average size of the clotted particle grain was 250 nm˜300 nm in cross section and 40 nm˜50 nm in height.

Meanwhile, in case of a ND powder after an acid treatment, as a result of a FT-IR analysis, it was possible to confirm that a COOH group was coupled to the surface of the ND since there was a peak which meant the presence of —COOH.

(2) Surface Modification into Hydrophobic State

2 g of the ND—COOH powder was added to 400 ml of SOCl₂ solution, and the mixture was reacted for 24 hours at 70° C., and the powder produced after the surplus SOCl₂ was rinsed with the THF was dried in a vacuum state. 40 g of octadecylamine was added, and the mixture was reacted for 4 days at 90˜100° C. Thereafter, the surplus octadecylamine was rinsed with ethanol which was boiled in a double boiler. The obtained particles from which ethanol was removed complete was stored in a vacuum state, whereby it was possible to obtain nano-diamond particles (ND-ODA) wherein octadecylamine groups were coupled to the surfaces thereof.

Embodiments 2 and 3, and Comparison Examples 1 to 8 Preparation of Engine Oil Additive Composition

According to the composition in Table 1 below, it was possible to prepare an engine oil additive composition in the embodiments 2 and 3 and the comparison examples 1 to 8.

According to the embodiments 2 and 3, the ND-ODA treated in the embodiment 1 was dispersed along with oleylamine using ultrasonic waves for 30 minutes. Polyalkenyl succinimide, oleic acid and a base oil (Ultra-S manufactured by S-oil company) were added and dispersed with ultrasonic waves for 3 hours.

TABLE 1 Preparation of Engine oil additive composition (% by weight) ND- ND ODA OLA SI OA ODA base oil embodiment — 0.005 0.058 0.032 1.641 — 98.264 2(sample 5) embodiment — 0.010 0.116 0.027 3.282 — 96.565 3(sample 6) comparison 0.005 — — —  0.0005 0.0005 99.994 example 1(sample 1) comparison — 0.010 — — — — 99.990 example 2(sample 3) comparison 0.01  — — — 3.425 — 96.565 example 3(sample 4) comparison — 0.010 — 3.425 — — 96.565 example 4(sample 7) comparison — 0.010 — — 3.425 — 96.565 example 5(sample 8) comparison — 0.010 2.778 0.647 — — 96.565 example 6(sample 9) comparison — 0.010 0.117 — 3.308 — 96.565 example 7(sample 10) comparison — 0.010 — 0.028 3.397 — 96.565 example 8(sample 11) ND: Nano-diamond before its surface is modified into a hydrophobic state. ND-ODA: Nano-diamond the surface of which is modified into a hydrophobic state and which is obtained in the embodiment 1, namely, (nanodiamond-Octadecylamide) OLA: (oleylamine) SI: (polyisobutenyl succinimide) OA: (oleic acid) ODA: (octadecylamine)

Meanwhile, in the table 1, the comparison example 1 was obtained as in the embodiments 1 and 3 of the Korean patent registration number 10-1205640 in such a way to dilute in the oil a mixture obtained by inputting nano-diamond, oleic acid and dodecylamine into an oil at a ratio of % by weight of 1:0.1:0.1 and processing the mixture for one hour with ultrasonic waves and a ball mill device.

In addition, the comparison examples 2 to 8 were prepared by the same method as in the second embodiment 2 by using the ND-ODA or ND and each dispersion agent shown in Table 1 or a combination of each dispersion agent.

<Test Evaluation>

1. Visual Observation

The samples of the embodiments 2 and 3 and the comparison examples 1 to 8 were prepared and observed visually with eyes. As a result of the observation, it was confirmed that precipitation had occurred in the samples of the comparison examples 2, 5, 6 and 7. In these samples, it seemed that the mixture was aggregated since the dispersion of the nano-diamond particles had not been appropriately performed.

Dispersion Stability Test

It was performed using a dispersion stability measurement equipment (LUMiSize by Youngjin corporation). The dispersion stability performance test instrument uses a method which is directed to measuring an absorbance of a lower portion of a cell where the particle has been precipitated by forcibly precipitating the particles in the solution in such a way to randomly apply gravity. The higher the transmittance at the lower portion of the cell where the precipitation has occurred, the better the dispersion stability.

The dispersion stability measurement device of LUMiSize is a device which is configured to measure a dispersion stability with the aid of a STEP technology (Space & time Resolved Extinction Profile Technology). As for the principle of the measurement, a de-mixing wherein the dispersion goes back to the state before the dispersion has occurred, in general occurs at an interval of a few months after the dispersion of the emulsion-emulsion or emulsion-suspension has occurred using the dispersion equipment (for example, a homogenizer, a homomixer, ultrasonic waves). This de-mixing procedure is most efficiently implemented within a very short time period, thus measuring dispersion stability.

TABLE 2 Measuring Measurement % at which dispersed Classification start time completion time particles sink per hour (sample No.) (min) (min) (%/min) embodiment 0.5243 10.02 0.0961 2(sample 5) embodiment 0.5262 10.02 0.0741 3(sample 6) comparison 0.4995 10.00 0.2784 example 1(sample 1) comparison 0.5082 10.01 * Initial precipitation example formation 2(sample 3) comparison 0.5095 10.01 0.2122 example 3(sample 4) comparison 0.5108 10.03 0.2244 example 4(sample 7) comparison 0.5418 10.03 * Initial precipitation example formation 5(sample 8) comparison 0.5568 10.04 * Initial precipitation example formation 6(sample 9) comparison 0.5583 10.04 * Initial precipitation example formation 7(sample 10) comparison 0.5738 10.05 0.2146 example 8(sample 11)

As confirmed in Table 2, the sinking speed was confirmed after 10 minutes using the dispersion stability measurement device of LUMiSize. As a result, it was confirmed that the sinking speed in the embodiments 2 and 3 were low 0.0961%/min and 0.0741%/min. That the sinking speed is low like that means that the dispersion state can be maintained stable for a long time since the dispersion stability is high. To this end, it is possible to confirm that the engine oil additive composition of the present invention has enhanced two or three times as compared with the conventional product.

Meanwhile, as seen in Table 2, in case of the comparison examples 2, 5, 6 and 7, as visually confirmed with eyes in the test evaluation 1, the precipitation has occurred at an initial stage after the engine oil composition was produced. To this end, it is confirmed that the dispersion has not been appropriately performed since the nano-diamond particles have been aggregated.

Namely, it is confirmed that the embodiments 2 and 3 corresponding to the engine oil additive composition of the present invention can allow to obtain an engine oil additive composition wherein nano-diamond particles are dispersed stable in the oil as compared with the comparison examples 1 to 8, and dispersion stability can be effectively maintained for a long time. In this way, the engine oil additive composition of the present invention may have a good dispersion stability for a long time since the nano-diamond particles the surfaces of which are modified into a hydrophobic state are used together with a specific dispersion agent, and the lubricating function of the engine oil can be enhanced by reducing friction coefficient. 

1. An engine oil additive composition, comprising: 60˜99% by weight of a base oil; 0.001˜0.5% by weight of a nano-diamond the surface of which is modified into a hydrophobic state; and a dispersion agent which is formed of 0.05˜10% by weight of oleylamine, 0.01˜5% by weight of polyalkenyl succinimide, and 0.5˜35% by weight of oleic acid, wherein the engine oil additive composition contains nano-diamonds.
 2. The composition of claim 1, wherein the nano-diamond the surface of which is modified into a hydrophobic state is prepared by: a process (first step) wherein the nano-diamonds are treated with one or more of acids selected from a group consisting of hydrochloric acid, nitric acid, sulfuric acid and hydrogen peroxide; a process (second step) wherein the nano-diamonds acid-treated in the first step are reacted with one or more of acid chlorides selected from a group consisting of thionyl chloride, phosphorous trichloride, and phosphorous pentachloride; and a process (third step) wherein the nano-diamonds obtained in the second step are reacted with alkyl amine having 16˜18 carbons.
 3. The composition of claim 1, wherein the polyalkenyl succinimide is polyisobutenyl succinimide.
 4. A method for preparing an engine oil additive composition, comprising: treating (first step) nano-diamonds with one or more of acids selected from a group consisting of hydrochloric acid, nitric acid, sulfuric acid and hydrogen peroxide; reacting (second step) the nano-diamonds acid-treated in the first step with one or more of acid chlorides selected from a group consisting of thionyl chloride, phosphorous trichloride, and phosphorous pentachloride; reacting (third step) the nano-diamonds obtained in the second step with alkyl amine having 16˜18 carbons, thus preparing nano-diamonds the surfaces of which are modified into a hydrophobic state; obtaining (fourth step) a dispersed thing by mixing the nano-diamonds the surfaces of which are modified into a hydrophobic state, with oleylamine and dispersing with ultrasonic waves; and inputting (fifth step) polyalkenyl succinimide, oleic acid, and a base oil into the dispersed thing obtained in the fourth step and dispersing with ultrasonic waves. 